[OT] HS Tariff code for assembled pcbs?

To say I'm confused is an understatement :)

I had a problem recently shipping a small assembled pcb to Germany from 
the UK - it was returned with a note saying 'non-compliant to customs 
regulations' because of 'missing or deficient' customs form CN22.

I used a customs form, CN22 and this requires a "HS Tariff no" for the 
item shipped but I haven't been filling in a code. It looks like I'll 
need to from now on. Possibly customs are tightening up, but German 
customs do appear to be particularly fussy, I've had an issue before 
with them.

Looking online there are lots of sites indicating the correct tariff 
code would be in Chapter 85, but the minor categorisations of components 
on assembled boards are rather weird and don't make much sense to me.

So far I've concluded something like 8534.00 is near but then this seems 
to be just for bare boards and possibly 8534.00.70 is more accurate for 
an assembled one. I don't want to have to use different codes for 
slightly different boards if it can be helped.

The USA codes seem to have more details/digits required but maybe the 
result would be good for elsewhere in the World.

Here are links to a couple of boards, I'd be grateful for other's 
experiences with choosing HS Tariff codes for boards like these:

https://easy-driver.co.uk/wp-content/uploads/2023/08/ED88A2.jpg (these 
are mostly shipped to USA without issues so far)

https://easy-driver.co.uk/wp-content/uploads/2024/12/16A-cropped.jpg 
(could be shipped anywhere)

John